DRAM memory cell sizes continue to decrease. For example, memories which store 64 Mb of information are now in production with plans to implement 256 Mb and 1 Gb memories soon. These high density memories have a design rule of a minimum 0.35 .mu.m or less. As the cells get smaller, conventional dielectrics such as nitride/oxide (N/O) can hardly supply sufficient storage capacitance. This requirement is due to the fact that N/O materials have a low dielectric constant of about seven. In general, a simple formula can be used to express capacitance, namely C.sub.s /A=.epsilon..sub.0 .epsilon..sub.r /t, where C.sub.s represents storage cell capacitance, A is the total surface area of the capacitor, t is the dielectric film thickness, and .epsilon..sub.0 and .epsilon..sub.r stands for vacuum and relative permitivities, respectively. To increase capacitance, complicated cell structures including multiple fins and disks have been proposed to increase the surface area between the plates and dielectric. These complex cell structures, however, are difficult to fabricate and, therefore, not suitable for manufacturing.
Storage capacitors using high dielectric constant (k) materials including tantalum pentoxide (Ta.sub.2 O.sub.5), barium strontium titanate (BST), strontium titanate (SrTiO.sub.3), and lead zirconium titanate (PZT) have been proposed as dielectrics for simple cell structures including simple stacked cell (STC). The high dielectric constant of these materials give sufficient storage capacitance. Unfortunately, high dielectric constant materials including BST, SrTiO.sub.3, and PZT are difficult to form using standard processing techniques. For example, it is difficult to control dielectric composition.
Although Ta.sub.2 O.sub.5 has a dielectric constant of about 25 compared with BST's dielectric constant of about 400, the Ta2O.sub.5 capacitors are much easier to fabricate than BST capacitors. Ta.sub.2 O.sub.5 capacitors, however, usually have high leakage current density. Therefore, a need exists for a process of forming a high dielectric capacitor which overcomes many of the problems of the prior art.